76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
/*
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include "brw_reg.h"
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union fu {
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float f;
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unsigned u;
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struct {
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unsigned mantissa:23;
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unsigned exponent:8;
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unsigned sign:1;
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} s;
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};
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int
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brw_float_to_vf(float f)
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{
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union fu fu = { .f = f };
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/* ±0.0f is special cased. */
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if (f == 0.0f)
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return fu.s.sign << 7;
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unsigned mantissa = fu.s.mantissa >> (23 - 4);
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unsigned exponent = fu.s.exponent - (127 - 3);
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unsigned vf = (fu.s.sign << 7) | (exponent << 4) | mantissa;
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/* 0.125 would have had the same representation as 0.0, so reject it. */
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if ((vf & 0x7f) == 0)
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return -1;
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/* Make sure the mantissa fits in 4-bits and the exponent in 3-bits. */
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if (fu.u & 0x7ffff || exponent > 7)
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return -1;
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return vf;
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}
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float
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brw_vf_to_float(unsigned char vf)
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{
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union fu fu;
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/* ±0.0f is special cased. */
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if (vf == 0x00 || vf == 0x80) {
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fu.u = (unsigned)vf << 24;
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return fu.f;
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}
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fu.s.sign = vf >> 7;
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fu.s.exponent = ((vf & 0x70) >> 4) + (127 - 3);
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fu.s.mantissa = (vf & 0xf) << (23 - 4);
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return fu.f;
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}
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